Segmental abrasive wheel



Sept. 24, T1929u T. LARSSON ET Ax..

SEGMENTAL ABRAS IVE WHEEL Filed May 19, 1924 Patented Sept. 24, 1929STATES treni* ori-ICE THURE LARSSON AND HUGO W. H. BETH, OF WORCESTER,MASSACHUSETTS, ASSIGNORS TO NORTON COMPANY, OF WORCESTER, MASSACHUSETTS,A CORPORATION OF MASSACHUSETTS SEGMEN TAL ABRASIVE WIEEL Applicationfiled May 19, 1924. Serial No. 714,322..

An attempt has been made to use ceramic bonded articial abrasives forsuch wheels but it has been found that they break easily or theircorners chip off., thus making the use of such wheels expensive. Owingto problems met in manufacturing` it has been found desirable to makethe pulp grinding stone of a number of segments, andto clamp thesetogether to form the complete wheel; but the necessity for driving thestone under the enormous restrainingr pressure of heavy logs heldagainst the wheel has made it difficult to mount the segments on aspindle and clamp them between driving' flanges without increasing theliability of breakage.

lt is, accordingly, an object of our invention to provide an improvedgrinding wheely of this type which may be economically man ufactured andeasily assembled, which will give a long and elicient life of service,andl which is so constructed that the abrasive material will not becomecracked or broken due to the heat expansion or the frictional strains ofnormal usage.

It is a further object of our invention to provide an improved mountingfor the segmentsof a wheel whereby the segments may be held rigidly inposition under a clamping pressure which is so uniformly distributedthat the driving flanges may be adjusted tightly in place withoutserious results.

lVith these and other objects in view, as will be interned in thefollowing enclosure, our invention resides in the combination of partsset forth in the specification and covered by the claims appendedhereto.

Referring to the drawings. in which like reference numerals indicatelike parts:

Fig. l is a section on the line l-l of Fig. 2 showing one embodiment ofour invention;

Fig. Q is a vertical central section through' the grinding wheel; and

Fig. 3 is an enlarged sectional detail show- 1n g the mounting of theabrasive segments.

@ne embodiment of our invention may comprise a grinding wheel made up ofa plurality of rows vof closely positioned abrasive segments mounted ona rotatable support, such as a drum. These segments may be secured inposition by means of clamping flanges or plates engaging the exposedfaces of the end segments on the wheel which are so mounted that theymay be adjustahly moved toward each other to clamp the segments firmlytherebetween. The segments are so shaped that they will lie closetogether adjacent to the cylindrical grinding surface of the wheel; andbetween the inner faces of adjacent segments is a clamping or frictionmember which serves when the clamping flanges are adjusted into positionto frictionally or otherwise engage the inner sides of the segments andaid in holding them in position. rThe clamping or friction member, whichmay be in the shape of a ring mounted in an annular groove formedbetween adjacent faces of the segments, is freely movable parallel withthe axis of the wheel and relative to the surface of the drum, so thatthe pressure of the clamping flanges may be distributed throughout thewheel. The surface of the wheel is made up of a large number of smallabrasive segments to minimize the liability7 of breakage from heat eX-pansion; and in order that the segments may be supported laterally andprotected from forces tending to break the Wheel, the crevices arefilled adjacent to the surface of t-he wheel with a filler, andpreferably one of a cementitious nature, which will unite with the sidesof the segments and form them into an integral solid body.

As shown in the drawings, a wide faced wheel may be formed of 'aplurality of disk shaped rovs 10 of segments which are so formed andarranged as to provide a cylindrical grinding surface ll. The segmentsl2 may be individually shaped, as shown in the drawings, as quadrants orin other suitable forms, and their inner surfaces are made concave so asto form an internal cylindrical surface 18 which will fit on a rotatablesnpport andso position the segments properly.

The rotatable support may be Ishaped as a large drum 15 which has anouter cylindrical surface, and this drum is in turn removably mounted ona` spindle or driving shaft 16 by means of the annular webs 17 whichhave a sliding fit on the shaft.

In order to clamp in position these rows 10 of abrasive segments and todrive them ro- `tatively, we provide end flanges or driving members 2Owhich have central openings 21 screw threaded to the spindle 16. 'Ihethreads ofthe two driving flanges are so disposed, one a right-handthread and the other a left-hand thread, that rotation of the spindle 1Gin normal operation tends to tighten the hold ofl the flangesupon theabrading elements. As illustrated, these flanges project beyond theouter periphery of the drum and the assembled abrading disks are of suchwidth thato they project slightly beyond the ends of the drum so thatthe flanges may be clamped against the outer surfaces of the endsegments.

In order to transmit the clamping pressure uniformly throughout theabrading wheel and'to prevent breakage of the same, we providefrictional driving rings 24,'Whose inner peripheries are such as to fitupon the outer surface of the drum and the outer peripheries are asgreat as those of the driving anges 20. In order that the adjacent edgesof the rows of abrasive Isegments may be close together, we cut a groove25 in the inner faces of each segment in one row of such a size anddepth that a ring 24 may lit therein. These rings j may have parallelplane faces 26 and 27, butl we prefer to make them slightly wedge shapedin order to assist in holding the abrasive segments in place, andparticularly in case of breakage of any of the segments. To this end,each groove 25 is made slightly shallower adjacent the inner peripheryof the wheel, and each ring 24 is provided with a tapering face on oneside to fit the groove. The other side of the ring is made. parallelwith the plane face 29 of the other side of the adjacent row of segmentswhich lies in a diammetrical plane of the wheel.

Since the two faces of each adjacent row of segments should heaccurately made, we may provide each side 29 with a central raisedportion 30 whichmay be trued off to the desired extent 'to make acareful driving fit. In order thatall abrasive segments may be madealike, it will be observed that one-half of them are shown in Fig. 1 asfacing in one direction and the other half inthe other, so that at thecenter of the wheel, two of the wedging and segments make close litswith each other and with the rings, so that the pressure is evenlydistributed and each segment is subjected to lthe same driving forces.This arrangement of frictional driving and locking rings between eachpair of adjacent abrasive seg: ments provides such a mounting that thewheel may be subjected to the enormous pressures involved in grindingwood pulp without danger of breaking the wheel under normal usage.

`'Ihis type of grinding wheel is particularly adapted for grinding woodpulp in which operation logs are held against the peripheral surface ofthe wheel under high pressure. If the wheel is intended for such severeusage, We propose to fill the crevices, and particularly adjacent to thecylindrical grinding surface, with a filler, and preferably acementitious filler, such as cement, which will adhere to the segmentsand unite them into a rigid, unitary wheel structure. This fillersupports the sides of the segments so that any lateral thrust will'betransmitted easily from one segment to another and thus be absorbedwithout endangering the wheel. Also, it prevents slivers of wood or thelike from lodging in the crevices between the segments and sopassingthrough the grinding zone and thus producing an inferior grade of woodpulp. Moreover, if the crevices betweeen the segments are filled to theouter cylindrical surface of the wheel, there are no projections ordepressions for the logs to bump or strike forcibl against, and sooneror later break off chips rom the Wheel. In this way the life of theWheel is materially lengthened. It is also to be explained that theclamping or friction members 24 may be made of suitable metals, such aslead or other soft materials, which may have agood driving hold on theabrasive segments or otherwise serve the purposes specified.

`Having thus described our invention, what we claim as new and desire tosecure by Letters Patent is: .j

1. A wood pulp grinding wheel comprising a rotatable support, aplurality of rows of abrasive segments arranged thereon to form acylindrical grinding surface, a freely movable friction member locatedbetween and in engagement with the inner faces of adjacent segments, andclamping flanges associated with therotatable support and adjust- 4ablyengaging the exposed faces of the end `in the drum to support the same,the inner opposed faces of adjacent segments having a groove, a freelymovable, friction member lli together adjacent to the wheel periphery,

and clamping flanges adjustably mounted on the spindle and engaging theexposed faces of the end segments which serve to press the segments andfriction members into frictional contact and to hold the segments on thedrum.

3. A grinding wheel comprising a rotatable support, a plurality ofrowsof abrasive segments arranged thereon to form a cylindrical grindingsurface, a freely movable clamping member between and engaging the innerfaces of adjacent segments, clamping members associated with the supportand serving to press the segments and the freely movable clamping membertogether and to hold them in assembled relation, and a iilling materialin the crevices between the segments adjacent to the' grinding surface.

4. A grinding wheel comprising a wide drum, a spindle to support thesame, a plurality of rows of narrow abrasive segments on the drumarranged to form a cglindrical grinding surface, the inner faces oadjacent segments which are parallel with the wheel ends being closelypositioned and shapedto form a groove therebetween, a freely movableclamping member', which is independent of the drum located in the grooveand frictionally engaging the sides thereof, clamping flanges engagingthe end faces of the wheel and cooperating with the drum to press thesegments and clamping member together and to hold the segments inposition', anda cementitious filler in the crevices between the segmentswhich unites them into va rigid Wheel structure.

5. A grinding wheel comprising a substantially cylindrical support, aspindle mounti able therein, a plurality of annular rows of abrasive sements on said support and arranged to orm a cylindrical grinding sur-4face, the inn r sides of adjacent rows of seg-v ments being shaped toform an annular groove, a freely movable ring in the groove having facesfrictionally engaging the segments, clamping flanges independent of saidsupport which are adj ustably mounted on the spindle and engage theouter faces of the segments and thereby. serve to force the segments andring into frictional contact, and a cementitious filler in the crevicesbetween'adjacent segments which unites the segments and support intofarigid wheel structure.

Signed at Worcester, Massachusetts, this 17th day of May, 1924.

HUGO W. H. BETH. THURE LARSSON.

